1. Field of the Invention
The present invention relates to an electrophotographic photoreceptor suitably usable for image forming apparatuses such as laser printers and LED printers.
2. Brief Description of the Related Art
Recently, electrophotographic photoreceptors using organic photoconductive compounds have been actively researched and studied because of, for example, their lighter weight, smoother surface, lower toxicity, greater ease of production, and lower costs than those of electrophotographic photoreceptors using inorganic photoconductive compounds. As the electrophotographic photoreceptors using organic photoconductive compounds, so-called layered photoreceptors have attracted particular attentions, and various materials have been proposed therefor. In the layered photoreceptors, the functions of the photoreceptor are achieved separately by a charge generation material and a charge transport material. In this mode, a highly sensitive electrophotographic photoreceptor may possibly be obtained by using in combination a material having a high carrier generation efficiency (carrier represents charge, hereinafter the same) as the charge generation material, and a material having a high charge transport capability as the charge transport material.
As the charge generation substances, various azo compounds and phthalocyanine-based compounds have been developed and put into practical use. Meanwhile, examples of the charge transport materials include carbazole derivatives (Japanese Patent Application Publication No. Hei 9-295969), phenothiazine derivatives (Japanese Patent Application Publication No. Hei 10-59952), tris(styrylphenyl)amine-based compounds (Japanese Patent Application Publication No. Sho 64-13553), and the like. However, the tris(styrylphenyl)amine-based compounds cannot be said to have sufficient solubilities in polymer binders and organic solvents. Moreover, even if films can be formed from the tris(styrylphenyl)amine-based compounds which are somehow made soluble, electrophotographic photoreceptors using these films do not have sufficiently high carrier mobilities. Accordingly, it cannot be said that electrophotographic photoreceptors with high sensitivity, low residual potential, and stable film state have been obtained.